Simultaneous solution strategies for inclusion of input saturation in the optimal design of dynamically operable plants

Recent work has considered the inclusion of input saturation in optimization-based integrated plant and control system design. Two mathematical formulations have been derived which allow saturation to be included within a simultaneous optimization framework; these are mixed-integer and bilinear formulations. The MIP formulation applied within an integrated design and control framework was found to be computationally intensive. This paper reviews these formulations and proposes an alternative solution strategy that uses an interior point approach to handle the complementarity constraints present in the bilinear formulation. A solution algorithm is presented and applied to an example problem.